1. Field of the Invention
The present invention generally relates to devices having a resin package such as semiconductor devices, and more particularly to a resin-sealed semiconductor device of a leadless surface mounting type directed to high-density mounting. Further, the present invention is concerned with a method of producing such a semiconductor device.
Recently, down-sizing of electronic devices has required a decrease in the pitch of leads extending from a resin-sealed type package. Hence, it is desired that there are provided a new structure of the resin-sealed type package making it possible to further decrease the lead pitch and a method of producing such a structure.
2. Description of the Related Art
FIGS. 1A, 1B and 1C are diagrams of a semiconductor device having a conventional resin-sealed package. The device includes a resin 1, a chip 2, outer leads 3, bonding wires 4 made of an alloy of gold and aluminum (Au--Al), and a die pad 5. The package shown in FIGS. 1A, 1B and 1C is called an SSOP (Shrink Small Outline Package). The outer leads 3 are bent in a gull-wing shape, and are mounted on a circuit board.
FIG. 2 is a cross-sectional view of a semiconductor device of another type. The device shown in FIG. 2 includes solder balls 6 and a mount base 7 on which the chip 2 sealed by the resin 1 and solder balls 6 are provided. The package shown in FIG. 2 is called a BGA (Ball Grid Array) type, and the solder balls 6 serve as terminals provided on the mount base 7.
The SSOP type package shown in FIGS. 1A, 1B and 1C has a disadvantage in which a large area 9 is needed to arrange inner leads 8 integrally formed with the outer leads 3, and a large area is needed to arrange the outer leads 3. Hence, the SSOP type package needs a large mounting area.
The BGA type package shown in FIG. 2 is expensive because it needs the mount base 7.